Infections in Pregnancy

Infections can occur during pregnancy which can be viral, bacterial or fungal and can affect the course of the pregnancy. Listed below are certain infections that may be encountered.

Viral infections

Varicella (Chicken pox)

Varicella or chickenpox is usually a childhood viral illness to which the vast majority of the population have been exposed and as a result have lifelong immunity. The infection is usually acquired by close contact with an individual or a child who currently has the infection and is shedding viral particles. Most pregnant women are immune to this infection and this can be confirmed by a blood test. In the absence of immunity, a susceptible pregnant women who has been exposed can be given Varicella-Zoster Immune Globulin (VZIG) to minimize the effect of the infection to both the mother and foetus. The VZIG must be given within 96 hours of exposure in order for it to be effective.

Parvovirus B19 (Slapped-cheek disease)

Infection with parvovirus B19 commonly occurs in children where it causes a mild respiratory illness with a characteristic ‘slapped-cheek’ rash on the face. Outbreaks of this infection are seen in child care centres. The virus is very infectious and adults of childbearing age can become infected if not previously exposed. Infection during the 1st half of the pregnancy can have serious implications for the foetus in utero. An antibody test can be done during pregnancy to determine susceptibility or confirm whether infection has occurred. As there is no treatment for this viral illness, avoiding contact with children in day care centres who have a febrile illness and rash is probably the best way to prevent exposure.

Bacterial infections

Listeria monocytogenes

Listeria infection is an illness caused by the ingestion of food contaminated with a bacteria known as Listeria monocytogenes. This bacteria is widespread within the environment and can be found in a variety of foods such as raw meat, vegetables, processed foods and contaminated dairy products. Symptoms of infection may appear from 3 days and up to 3 weeks after eating affected food and include fever, headache, tiredness, diarrhoea, nausea and abdominal cramping. In pregnant women infection may take the form of a mild illness which may subsequently lead to miscarriage or premature labour. The foetus is particularly at risk and therefore during pregnancy the mother should avoid certain high risk foods:

soft cheeses – brie, camembert, ricotta and fetta

uncooked seafood – smoked fish and mussels, oysters, sashimi, sushi

preprepared salads – coleslaw, fresh fruit salad

precooked meat products – pate, ham, salami

dips and salad dressings

soft serve ice-cream

Any food that has been cooked is safe to eat and it must be remembered that infection with Listeria is very uncommon in our community.

Group B Streptococcus

Group B Streptococcus (Group B Strep or GBS) is a bacterium that normally lives in the lower intestine and vagina of healthy women. In Australia it is estimated that 20% of women carry this organism in the vagina. These women are said to be ‘colonized’ with GBS. They are not unwell and are not contagious and do not require any treatment. The baby can be exposed to this bacteria during labour particularly if the labour is long and multiple vaginal examinations have been performed. If the baby picks up the bacteria during labour, it can develop serious infections (pneumonia, blood infections and meningitis) from the GBS. The infection is usually acquired as the baby passes down the birth canal of a colonized mother or if the GBS bacteria travel into the uterus after the membranes rupture (waters break). About 1 – 2% of babies born to a colonized mother will develop a serious infection with premature babies being particularly at risk.
The presence of GBS is determined by performing a vaginal swab at 36 weeks gestation. Mothers who are positive for GBS are given intravenous antibiotics (usually penicillin) during labour which considerably reduces the risk of baby becoming infected. For maximum effect, two doses need to be given 4 – 6 hours apart and at least 4 hours before delivery. For this reason it is important that women who are GBS positive contact the Birthing Suite as soon as the membranes rupture or labour starts so that antibiotic treatment can be commenced.

Ureaplasma urealyticum

This bacteria can be found in the lower genital tract of women, colonizing the vagina and cervix but infrequently causing any clinical symptoms apart from a slight vaginal discharge. Ureaplasma is acquired by sexual contact which may have occurred many years previously with the patient often being an asymptomatic carrier of the microorganism. In pregnancy involvement of the cervix by Ureaplasma urealyticum can cause an ascending intrauterine infection to cause many complications such as spontaneous miscarriage and later in pregnancy, preterm labour and preterm rupture of the membranes with significant morbidity for the premature infant. Ureaplasma is detected by taking swabs from the cervix and vagina and once confirmed it can be treated with antibiotics in the form of Erythromycin usually for the remainder of the pregnancy.

Mycoplasma hominis is another organism within the same class as Ureaplasma which can cause similar problems and complications during pregnancy.

Gardnerella vaginalis

This microorganism is the cause of bacterial vaginosis (BV) which is an overgrowth of Gardnerella vaginalis and other related bacteria. It commonly causes a watery grey, malodourous discharge which often has been present for some time. Gardnerella vaginalis when present during pregnancy has been implicated as a cause of intra-amniotic infection with similar sequelae of preterm labour and preterm rupture of membranes. Treatment consists of Metronidazole 400mg x3 times daily for 7 days.

Fungal infections

Candida albicans

Vaginal infection with the yeast Candida albicans occurs commonly during pregnancy particularly in the 3rd trimester. It causes vulval irritation and itching and may be associated with a discharge. Diagnosis is established by taking a vaginal swab which is sent for culture. Effective treatment requires appropriate antifungal therapy in the form of Canestan pessaries inserted within the vagina for 6 nights.